Imaging device, imaging system, and method for driving imaging device

An imaging device comprising:

• a first photoelectric conversion portion which converts light into an electric charge;
• a second photoelectric conversion portion which converts light into an electric charge;
• a first charge holding portion which holds an electric charge;
• a second charge holding portion which holds an electric charge;
• a first transfer transistor which transfers an electric charge of the first photoelectric conversion portion to the first charge holding portion;
• a second transfer transistor which transfers an electric charge of the second photoelectric conversion portion to the second charge holding portion;
• a first amplifier portion which outputs a signal based on an electric charge of the first charge holding portion;
• a second amplifier portion which outputs a signal based on an electric charge of the second charge holding portion;
• and
• an addition transistor for electrically connecting the first charge holding portion and the second charge holding portion, wherein
• in a state in which the addition transistor is turned on, both of the first transfer transistor and the second transfer transistor are being on,
• a difference between a control voltage provided, in a state in which the addition transistor is being off, to the first transfer transistor to turn on the first transfer transistor and a control voltage provided to the first transfer transistor to turn off the first transfer transistor is smaller than a difference between a control voltage provided, in a state in which the addition transistor is being on, to the first transfer transistor to turn on the first transfer transistor and the control voltage provided to the first transfer transistor to turn off the first transfer transistor, and is smaller than a difference between a control voltage provided, in a state in which the addition transistor is being on, to the second transfer transistor to turn on the second transfer transistor and a control voltage provided to the second transfer transistor to turn off the second transfer transistor, and
• a difference between a control voltage provided, in a state in which the addition transistor is turned off, to the second transfer transistor to turn on the second transfer transistor and a control voltage provided to the second transfer transistor to turn off the second transfer transistor is smaller than the difference between the control voltage provided, in a state in which the addition transistor is being on, to the first transfer transistor to turn on the first transfer transistor and the control voltage provided to the first transfer transistor to turn off the first transfer transistor, and is smaller than the difference between the control voltage provided, in a state in which the addition transistor is being on, to the second transfer transistor to turn on the second transfer transistor and the control voltage provided to the second transfer transistor to turn off the second transfer transistor.

An imaging system comprising:

• an imaging device including
• a first photoelectric conversion portion which converts light into an electric charge;
• a second photoelectric conversion portion which converts light into an electric charge;
• a charge holding portion which holds an electric charge;
• a first transfer transistor which transfers an electric charge of the first photoelectric conversion portion to the charge holding portion;
• a second transfer transistor which transfers an electric charge of the second photoelectric conversion portion to the charge holding portion;
• and
• an amplifier portion which outputs a signal based on an electric charge of the charge holding portion, wherein
• in a first control operation, from a state in which both of the first transfer transistor and the second transfer transistor are off, the first transfer transistor is turned on while the second transfer transistor remains off;
• in a second control operation, both of the first transfer transistor and the second transfer transistor are being on;
• and
• a difference between a control voltage provided in the first control operation to the first transfer transistor to turn on the first transfer transistor and a control voltage provided to the first transfer transistor to turn off the first transfer transistor is smaller than a difference between a control voltage provided in the second control operation to the first transfer transistor to turn on the first transfer transistor and the control voltage provided to the first transfer transistor to turn off the first transfer transistor;
• and
• a signal processing unit which processes a signal output from the imaging device.